A. Field of the Invention
The present invention relates generally to an endoscope for industrial use, or more particularly, to a pressure-tight endoscope for observing a high-pressure place.
B. Description of the Prior Art
An endoscope is generally used for observing a body cavity through illuminating an object and leading an image of it to an eyepiece in a grip portion of fiber-optic bundles or a lens system. Nowadays, such an endoscope is also utilized for an industrial service, for example, for examining the inner side of a high-pressurized gas tank.
By the way, the endoscope is made hermetic in order to prevent gathering of rust by moisture at the inner side of it when it is not used. Such an hermetic endoscope may, when it is inserted into a high-pressure place, easily may be deformed by the high-pressure there, or the hermetic construction may be broken, for example, such as an adhered portion of an observing window. Further, the operativeness of the flexible sheath may become difficult.